Method of polymerizing vinyl compounds



Patented l5, 1946 v v the reaction was rather slow since thetemperatrapping an in them and two were connected tlon. NaBOa.4H-2Obased onthe monomers. Charges UNITED STATES PATENT OFFICE METHOD OFPOLYMERIZING VINYL I COMPOUNDS William I). Wolfe, Cuyahoga Falls, Ohio,assignor to Wingloot Corporation, Wilmington, Del., a corporation ofDelaware No Drawing. Application October 12, 1940,

Serial No. 360,953

1 Claim. (01.260-845) This invention relates to an improved methodButadlene g 150 T 1' p l m ri lng a plurality of monomeri com-Methacrylonitril -g 67 pounds and, more particularly, to a method of(LCh I 5- p lymerizing a butadiene and acrylonitrile, 0 7.76 N NaOH .cc1.4

In the preparation of rubber-like masses from 5 NaBOaAHzO -g- 1.4certain unsaturated compounds, one method em- A 2.5% solution of Aresket#300 (a sodium ployed is to heat the substances in an aqueous sulfonateof an alkyl substituted biemulsion containing an emulsifying agent andphenyl) r g v250 an oxidant, catalysts and modifying ingredients, alsobeing sometimes present. This reaction is 1 conducted at a rather lowtemperature, tempera- .7 wires, from about room temperature up to 809The bottles and contents were chilled to to 80 C. for a final fillingwith butadiene. Two being customarily employed, and a temperature a of50 0. being usually preferred. Until recently, of the bottles wereclosed at this temper ture Aliquot portions of the above batch werestored in glass bottles provided with screw cap closures.

.15 with a a m a rin a r tus and allowed to ture was low and could notbe increased greatly warm i g ggz' after a VOL clue to-the unfavorableeffect on the properties ume of gas d escapedfrbm each which, was Henceit is about 3.5 times the volume of the air space. above tant tomaintain as favorable conditions for the the charge This wasaccomplished after the reaction as possible.

, butadiene had begun to boil rather freely, the Heretofore, it has notbeen observed that the procedure being l t d t r move essentiallyfltmsphere Surrounding the charge had any all of the air that was in thecold bottles. The efiect the Polymerization, where attention two pairsof bottles were then agitated for a has been paid to this fact, it hasbeen suggested period of 140 hours at 50 C. At the end of this thatoxygen in the atmosphere had a favorable time, it wasfound that nopolymer whatever had infillence- It has now been diScOVered that. formedin the bottles which .contained air but actua ly oxygen in comparativelysmall ts considerable copolymer was round in those from definitelyinhibits the copolymerization of butawhich the air had been removed, ayield oi 80% diene and aorylonitrile, as well as that or other beingobtained from one bottle.

similar monomers. Indeed, oxygen in amount as In other experimentsemploying he same techlittle as 0.7%, preferably not over 0.5%, of thenique as that described above'for removing oxyweight 01' the combinedmonomers proves sufli gen, mixtures of various mommers Save the cient tocompletely inhibit polymerization of l lowing'results:

butadiene and acrylonitrile during a period of 20 hours at a temperatureof 38 C. At the same Polymer yield time, charges which were maintainedunder the 1 j same conditions but which had been excluded 9 Hours tflAirpmnt Air erfrom contact with an atmosphere containing oxygen gaveyields of at least 80% of copolymer. 40-

This efiect is surprising and not to be expected styrene 7m 'fifi hig,,igfii, since the copolymerization requires the presence nutedlene-ocistyrene- 11s 0 7 1 1 m of an oxidant in the emulsion itself, a substance'ltifgfifiifiTfPfiffi 38 10.5- 8.3 34. 540.4 such as sodium perborate,which readily evolves +w 32 oxygen, being used. Despite the necessityfor an oxygen-yielding material in the charge, it h Further tests werethen run on batches made n e d fi i y established at f e xy n up ofbutadiene and acrylonitrile in 60:40 ratio, in the atmosphere in contactwith the emulsion emulsified in 2.5% aqueous solution of a sodium m beavoided f r best results. the charge comsulfuric acid ester of higherfatty alcohols, i, e., m2 intimately into contact with this atmospherethose containing from 12 to 18 carbon atoms, and since it must beagitated during the polymerizain the presence or approximately 0.8% ofTo show the effect of oxygen on a copolymeriof this solution were placedin bottles and known zation, a batch was made up containing thei'olvolumes of mixtures oi. oxygen and nitrosenin lowing ingredients:varying ratios were admitted, or, known volumes of oiwgen were admittedto bottles containing varying volumes of charge. By both methods, it wasfound that an amount of oxygen equal to about 0.7% of the weight of thecombined monomers proved sufficient to completely inhibit polymerizationin the system during a period of 20 hours at 38 During the same periodand at the same temperature control bottles from which oxygen had beeneliminated yielded at least 80% of copolymer.

The progressively increasing inhibiting eflect of oxygen on such chargesof butadiene and acrylonitrile in proportion to the amount of om!- genpresent was determined and tabulated. Thus,

:- er cent Orper cent Per cent in t e gas based on yield of mixturemonomers polymer 75. 0. 63 4. 7 90. 0. 74 None 100. 0. 85 None It willbe noted in the foregoing tabulation that a gas mixture was used inwhich the proportion resulting in corresponding decreases in the yieldof copolymer, until, at a point where the oxygen was about 0.7% on theweight of the monomers, polymerization was completely inhibited. ThusOla-Percent Percent on yield oi monomers polymer None 85. 0 0. 10 75. 40. 28 67. 2 0. 69 None 1. 98 None of the charge, definitely inhibiting.the desirability of excluding oxygen being known, this result can beachieved in any feasible manner. Thus, the air may be exhausted fromreaction vessels containing the charge to permit gaseous butadiene tooccupy the evacuated space, or the charge may be chilled and then warmedto permit the butadiene to sweep out the air. Al o. the charged vesselmay be evacuated and filled with an inert gas, such as nitrogen, or theair may be swept out with an inert gas. In short,

any practicable method of removing oxygen may be employed.

While the improved method is particularly eflective when applied to thepolymerization of butadiene and acrylonitrile in various proportions,such as butadiene and 40% acrylonitrile, it is also applicable to thepolymerization of other monomeric mixtures containing at least twomonomers, for example, butadiene-styrene, butadiene-i-ortho methylstyrene, butadiene+ ortho chloro styrene, butadiene+methyl methacryiate, butadiene-i-methacrylonitrile, butadiene-l-methyl itaconate,butadiene+methyl acrylate, and butadiene+ethyl acrylonitrlle, The methodcan also be applied to mixtures of three or more such monomericsubstances and, indeed, is generally applicable to emulsionpolymerizations. Likewise, emulsions of various constitutions may bemade up, the emulsifying agent, the oxidant and the catalyst beingvaried as described. Other oxidants which may be mentioned are benzoylperoxide, barium peroxide, hydrogen peroxide, etc. Other emulsifyingagents are alkylated methylene sulfonic acid sodium salts, so-

dium sulphonates of alkylated biphenyls, sodium sulphonates of highmelocular weight ether-alcohols, alkylated naphthalene sodiumsulfonates, etc. Other catalysts are ethylene dichloride, chloro benzeneand dichloro propionitrile.

While there have been described above certain preferred embodiments ofthe invention, the latter is not limited thereto, but only by theappended claimwherein it is intended to set forth all features ofpatentable novelty residing in the invention.

I claim:

In a method of preparing copolymers of butadiene-l,3 and an aliphaticacrylonitrile by polymerization in a medium containing an emulsifyingagent and a peroxide oxidant, the step which comprises agitating andheating the reaction mixture in a closed atmosphere containing oxygen inamount not over 0.5% by weight of the total monomers present, other thanthat combined in the form of water vapor.

' WILLIAM D. WOIFE.

Of course,

